def get_amplitudes(
self,
circuit: Circuit,
states: List[str],
valid_check: bool = True,
**kwargs: KwargTypes,
) -> Dict[str, complex]:
"""
Compute the complex coefficients of the final state.
Supported `kwargs` are as for `BraketBackend.process_circuits`.
:param states: classical states of interest, as binary strings of '0' and '1'
:returns: final complex amplitudes if initial state is all-zeros
"""
if not self.supports_amplitude:
raise RuntimeError("Backend does not support amplitude")
if valid_check:
self._check_all_circuits([circuit], nomeasure_warn=False)
bkcirc = self._to_bkcirc(circuit)
restype = ResultType.Amplitude(states)
bkcirc.add_result_type(restype)
task = self._run(bkcirc, n_shots=0, **kwargs)
res = task.result()
amplitudes = res.get_value_by_result_type(restype)
cdict = {}
for k, v in amplitudes.items():
# The amazon/sv1 simulator gives us 2-element lists [re, im].
# The local simulator gives us numpy.complex128.
cdict[k] = complex(*v) if type(v) is list else complex(v)
return cdict
def state_vector() -> ResultType:
"""Registers this function into the circuit class.
Returns:
ResultType: state vector as a requested result type
Examples:
>>> circ = Circuit().state_vector()
"""
return ResultType.StateVector()
def _get_result(completed_task: Union[AwsQuantumTask, LocalQuantumTask],
want_state: bool) -> Dict[str, BackendResult]:
result = completed_task.result()
kwargs = {}
if want_state:
kwargs["state"] = result.get_value_by_result_type(
ResultType.StateVector())
else:
kwargs["shots"] = OutcomeArray.from_readouts(result.measurements)
return {"result": BackendResult(**kwargs)}
def amplitude(state: List[str]) -> ResultType:
"""Registers this function into the circuit class.
Args:
state (List[str]): list of quantum states as strings with "0" and "1"
Returns:
ResultType: state vector as a requested result type
Examples:
>>> circ = Circuit().amplitude(state=["01", "10"])
"""
return ResultType.Amplitude(state=state)
def process_circuits(
self,
circuits: Iterable[Circuit],
n_shots: Optional[int] = None,
valid_check: bool = True,
**kwargs: KwargTypes,
) -> List[ResultHandle]:
"""
Supported `kwargs`: none
"""
if not self.supports_shots and not self.supports_state:
raise RuntimeError("Backend does not support shots or state")
if n_shots is None:
n_shots = 0
want_state = n_shots == 0
if (not want_state) and (n_shots < self._sample_min_shots
or n_shots > self._sample_max_shots):
raise ValueError(
"For sampling, n_shots must be between "
f"{self._sample_min_shots} and {self._sample_max_shots}. "
"For statevector simulation, omit this parameter.")
if valid_check:
self._check_all_circuits(circuits, nomeasure_warn=False)
handles = []
for circ in circuits:
bkcirc = self._to_bkcirc(circ)
if want_state:
bkcirc.add_result_type(ResultType.StateVector())
if not bkcirc.instructions and len(circ.bits) == 0:
task = None
else:
task = self._run(bkcirc, n_shots=n_shots)
if self._device_type == _DeviceType.LOCAL:
# Results are available now. Put them in the cache.
if task is not None:
assert task.state() == "COMPLETED"
results = _get_result(task, want_state)
else:
results = {
"result": self.empty_result(circ, n_shots=n_shots)
}
else:
# Task is asynchronous. Must wait for results.
results = {}
if task is not None:
handle = ResultHandle(task.id, want_state)
else:
handle = ResultHandle(str(uuid4()), False)
self._cache[handle] = results
handles.append(handle)
return handles
def density_matrix(target: QubitSetInput = None) -> ResultType:
"""Registers this function into the circuit class.
Args:
target (int, Qubit, or iterable of int / Qubit, optional): The target qubits
of the reduced density matrix. Default is `None`, and the
full density matrix is returned.
Returns:
ResultType: density matrix as a requested result type
Examples:
>>> circ = Circuit().density_matrix(target=[0, 1])
"""
return ResultType.DensityMatrix(target=target)
def probability(target: QubitSetInput = None) -> ResultType:
"""Registers this function into the circuit class.
Args:
target (int, Qubit, or iterable of int / Qubit, optional): The target qubits that the
result type is requested for. Default is `None`, which means all qubits for the
circuit.
Returns:
ResultType: probability as a requested result type
Examples:
>>> circ = Circuit().probability(target=[0, 1])
"""
return ResultType.Probability(target=target)
def variance(observable: Observable, target: QubitSetInput = None) -> ResultType:
"""Registers this function into the circuit class.
Args:
observable (Observable): the observable for the result type
target (int, Qubit, or iterable of int / Qubit, optional): Target qubits that the
result type is requested for. Default is `None`, which means the observable must
only operate on 1 qubit and it will be applied to all qubits in parallel
Returns:
ResultType: variance as a requested result type
Examples:
>>> circ = Circuit().variance(observable=Observable.Z(), target=0)
"""
return ResultType.Variance(observable=observable, target=target)
def sample(observable: Observable, target: QubitSetInput = None) -> ResultType:
"""Registers this function into the circuit class.
Args:
observable (Observable): the observable for the result type
target (QubitSetInput): Target qubits that the
result type is requested for. Default is `None`, which means the observable must
operate only on 1 qubit and it is applied to all qubits in parallel.
Returns:
ResultType: sample as a requested result type
Examples:
>>> circ = Circuit().sample(observable=Observable.Z(), target=0)
"""
return ResultType.Sample(observable=observable, target=target)
def _get_variance(
self,
bkcirc: braket.circuits.Circuit,
observable: Observable,
target: QubitSet,
n_shots: int,
**kwargs: KwargTypes,
) -> np.float64:
if not self.supports_variance:
raise RuntimeError("Backend does not support variance")
if n_shots < self._variance_min_shots or n_shots > self._variance_max_shots:
raise ValueError(
f"n_shots must be between {self._variance_min_shots} and "
f"{self._variance_max_shots}")
restype = ResultType.Variance(observable, target=target)
bkcirc.add_result_type(restype)
task = self._run(bkcirc, n_shots=n_shots, **kwargs)
res = task.result()
return res.get_value_by_result_type(restype) # type: ignore
def get_probabilities(
self,
circuit: Circuit,
qubits: Union[Iterable[int], None] = None,
n_shots: int = 0,
valid_check: bool = True,
**kwargs: KwargTypes,
) -> np.ndarray:
"""
Compute the (exact or empirical) probability distribution of outcomes.
If `n_shots > 0` the probabilities are calculated empirically by measurements.
If `n_shots = 0` (if supported) they are calculated exactly by simulation.
Supported `kwargs` are as for `BraketBackend.process_circuits`.
The order is big-endian with respect to the order of qubits in the argument.
For example, if qubits=[0,1] then the order of probabilities is [p(0,0), p(0,1),
p(1,0), p(1,1)], while if qubits=[1,0] the order is [p(0,0), p(1,0), p(0,1),
p(1,1)], where p(i,j) is the probability of qubit 0 being in state i and qubit 1
being in state j.
:param qubits: qubits of interest
:returns: list of probabilities of outcomes if initial state is all-zeros
"""
if not self.supports_probability:
raise RuntimeError("Backend does not support probability")
if (n_shots < self._probability_min_shots
or n_shots > self._probability_max_shots):
raise ValueError(
f"n_shots must be between {self._probability_min_shots} and "
f"{self._probability_max_shots}")
if valid_check:
self._check_all_circuits([circuit], nomeasure_warn=False)
bkcirc = self._to_bkcirc(circuit)
restype = ResultType.Probability(target=qubits)
bkcirc.add_result_type(restype)
task = self._run(bkcirc, n_shots=n_shots, **kwargs)
res = task.result()
return res.get_value_by_result_type(restype) # type: ignore
def add_result_type(
self,
result_type: ResultType,
target: QubitSetInput = None,
target_mapping: Dict[QubitInput, QubitInput] = {},
) -> Circuit:
"""
Add a requested result type to `self`, returns `self` for chaining ability.
Args:
result_type (ResultType): `ResultType` to add into `self`.
target (int, Qubit, or iterable of int / Qubit, optional): Target qubits for the
`result_type`.
Default = `None`.
target_mapping (dictionary[int or Qubit, int or Qubit], optional): A dictionary of
qubit mappings to apply to the `result_type.target`. Key is the qubit in
`result_type.target` and the value is what the key will be changed to.
Default = `{}`.
Note: target and target_mapping will only be applied to those requested result types with
the attribute `target`. The result_type will be appended to the end of the list of
`circuit.result_types` only if it does not already exist in `circuit.result_types`
Returns:
Circuit: self
Raises:
TypeError: If both `target_mapping` and `target` are supplied.
ValueError: If the observable specified for a qubit is different from what is
specified by the result types already added to the circuit. Only one observable
is allowed for a qubit.
Examples:
>>> result_type = ResultType.Probability(target=[0, 1])
>>> circ = Circuit().add_result_type(result_type)
>>> print(circ.result_types[0])
Probability(target=QubitSet([Qubit(0), Qubit(1)]))
>>> result_type = ResultType.Probability(target=[0, 1])
>>> circ = Circuit().add_result_type(result_type, target_mapping={0: 10, 1: 11})
>>> print(circ.result_types[0])
Probability(target=QubitSet([Qubit(10), Qubit(11)]))
>>> result_type = ResultType.Probability(target=[0, 1])
>>> circ = Circuit().add_result_type(result_type, target=[10, 11])
>>> print(circ.result_types[0])
Probability(target=QubitSet([Qubit(10), Qubit(11)]))
>>> result_type = ResultType.StateVector()
>>> circ = Circuit().add_result_type(result_type)
>>> print(circ.result_types[0])
StateVector()
"""
if target_mapping and target is not None:
raise TypeError("Only one of 'target_mapping' or 'target' can be supplied.")
if not target_mapping and not target:
# Nothing has been supplied, add result_type
result_type_to_add = result_type
elif target_mapping:
# Target mapping has been supplied, copy result_type
result_type_to_add = result_type.copy(target_mapping=target_mapping)
else:
# ResultType with target
result_type_to_add = result_type.copy(target=target)
if result_type_to_add not in self._result_types:
self._add_to_qubit_observable_mapping(result_type_to_add)
self._add_to_qubit_observable_set(result_type_to_add)
self._result_types.append(result_type_to_add)
return self
def __eq__(self, other) -> bool:
if isinstance(other, StateVector):
return True
return False
def __copy__(self) -> StateVector:
return type(self)()
# must redefine __hash__ since __eq__ is overwritten
# https://docs.python.org/3/reference/datamodel.html#object.__hash__
def __hash__(self) -> int:
return super().__hash__()
ResultType.register_result_type(StateVector)
class DensityMatrix(ResultType):
"""
The full density matrix as a requested result type.
This is available on simulators only when `shots=0`.
"""
def __init__(self, target: QubitSetInput = None):
"""
Args:
target (int, Qubit, or iterable of int / Qubit, optional): The target qubits
of the reduced density matrix. Default is `None`, and the
full density matrix is returned.
def add_result_type(
self,
result_type: ResultType,
target: QubitSetInput = None,
target_mapping: Dict[QubitInput, QubitInput] = None,
) -> Circuit:
"""
Add a requested result type to `self`, returns `self` for chaining ability.
Args:
result_type (ResultType): `ResultType` to add into `self`.
target (int, Qubit, or iterable of int / Qubit, optional): Target qubits for the
`result_type`.
Default = `None`.
target_mapping (dictionary[int or Qubit, int or Qubit], optional): A dictionary of
qubit mappings to apply to the `result_type.target`. Key is the qubit in
`result_type.target` and the value is what the key will be changed to.
Default = `None`.
Note: target and target_mapping will only be applied to those requested result types with
the attribute `target`. The result_type will be appended to the end of the dict keys of
`circuit.result_types` only if it does not already exist in `circuit.result_types`
Returns:
Circuit: self
Raises:
TypeError: If both `target_mapping` and `target` are supplied.
Examples:
>>> result_type = ResultType.Probability(target=[0, 1])
>>> circ = Circuit().add_result_type(result_type)
>>> print(circ.result_types[0])
Probability(target=QubitSet([Qubit(0), Qubit(1)]))
>>> result_type = ResultType.Probability(target=[0, 1])
>>> circ = Circuit().add_result_type(result_type, target_mapping={0: 10, 1: 11})
>>> print(circ.result_types[0])
Probability(target=QubitSet([Qubit(10), Qubit(11)]))
>>> result_type = ResultType.Probability(target=[0, 1])
>>> circ = Circuit().add_result_type(result_type, target=[10, 11])
>>> print(circ.result_types[0])
Probability(target=QubitSet([Qubit(10), Qubit(11)]))
>>> result_type = ResultType.StateVector()
>>> circ = Circuit().add_result_type(result_type)
>>> print(circ.result_types[0])
StateVector()
"""
if target_mapping and target is not None:
raise TypeError("Only one of 'target_mapping' or 'target' can be supplied.")
if not target_mapping and not target:
# Nothing has been supplied, add result_type
result_type_to_add = result_type
elif target_mapping:
# Target mapping has been supplied, copy result_type
result_type_to_add = result_type.copy(target_mapping=target_mapping)
else:
# ResultType with target
result_type_to_add = result_type.copy(target=target)
if result_type_to_add not in self._result_types:
observable = Circuit._extract_observable(result_type_to_add)
if observable and self._observables_simultaneously_measurable:
# Only check if all observables can be simultaneously measured
self._add_to_qubit_observable_mapping(observable, result_type_to_add.target)
self._add_to_qubit_observable_set(result_type_to_add)
# using dict as an ordered set, value is arbitrary
self._result_types[result_type_to_add] = None
return self
